My first was a 91, second a 97 (with paper gaskets) and they never failed, even after 50,000 miles of use. Nor did I have any upper roller problems. (third was an 09 that was stolen after 13,000 miles)
An old mechanics trick for air cooled VW engines was to always retorque the jug/head bolts to spec after break in. That's what I did on my first 2 DRs. (resultingly, never had a gasket failure)
Since I didn't have access to the internet back in 97, I never knew about the NSU screws and got lucky I guess. (when I bought my 09, I did loc-tite them).
In regards to the 96+ upper roller bearings, since I learned on the 91 that Suzuki doesn't know what grease is, while I had everything apart anyway to regrease things...Upon reassembly and with the shock still off, I ran the swingarm through it's range of travel to check for proper chain tension.
What I found out is that Suzukis recommended settings are too tight (with the upper chain roller in place) so that it binds.
I set the chain to proper tension (looks incredibly loose compared to their specs while at rest) so that it was just snug while going through its tightest range of travel (when it contacts the upper roller which I left in place).
Those rollers keep your chain from jumping off the front sprocket when you have your chain adjusted properly with the upper roller in place.
That's its purpose. (a purpose un-needed if you remove the roller and keep the spec set to their original specs)
It really is a catch 22 deal. Because, without the roller in place, you can set the chain spec to suzukis recommended specs and be good. With it in place, you have to set it loose to avoid binding and utilize the roller to keep the chain from jumping teeth.
Basicly, I'm posting this to show you have 2 choices for chain spec with or without rollers. (50,000 miles with no broken pieces showed me it was possible to leave the rollers intact without issue)(but you need to take the time to run the swing arm through it's range of motion to adjust the chain properly)
I wont argue the above...I'm not disagreeing with the anti-roller crowd, just showing there are 2 options for adjustments and no problems. B.T.W. I'm fat and always bottomed out the stock suspension and put stress on those components.
Another tip for the back country....
Carry a hacksaw (or blade and vise grips) enough rubber hose of the right diameter, and 2 hose clamps and a screwdriver.
Reason, if you smash a hole in that tiny little oil cooler, you can mcguyver a bypass and easily get home without the cooler. I managed to do that on the old 91 and used her for around 10,000 miles with no oil cooler at all. (you can do the same fo the 96+)
Biggest problem area I've ever had with any of my DR's were loose head bearings. Give the things about 1,ooo miles of break in and then retorque things there as well.
I'm most curious about those of you who have had electrical issues.
I always ran grip heaters, 80/100watt headlight bulbs and even an aux 50watt fog light at times and never had any issues with batteries or anything else.
Makes me wonder IF the DR doesn't do better with a larger load on it's system. (note: I rode almost every day and the battery was always fully charged)